Emergency Radio Warning System

ABSTRACT

A radio warning system includes emergency condition sensors for actuating respective radio transmitters which are modulated by identification generators to produce identification signals which contain one or more frequencies selected from groups of four frequencies in accordance with selected identifying binary coded decimal digits. A transmitted identification signal is detected by a radio receiver in a mobile unit or central dispatch location to operate a memory and a decimal display unit to indicate the existence and location of the emergency condition until reset by an operator. The transmitters are deactuated by a timing circuit after a predetermined period. Delay circuitry prevents operation of the memory and decimal display unit until the identification signal has been received for a predetermined continuous duration.

United States Patent [191 Worsham et a].

[ 1 Feb. 4, 1975 1 EMERGENCY RADIO WARNING SYSTEM [73] Assignee:Criminalistics, lnc., Opa Locka, Fla.

[22] Filed: Dec. 18, 1972 [21] Appl. No.: 315,856

[52] U.S. Cl 340/224, 325/64, 340/171 PF [51] Int. Cl 1104b 7/00, H04q11/02 [58] Field of Search 325/64, 18; 340/224, 171,

340/171 PF, 171 R [56] References Cited UNITED STATES PATENTS 3,035,2505/1962 Durkce ct a1. 340/171 PF 3,304,501 2/1967 Ruthenberg 325/64 X3,581,208 5/1971 Buehrle, Jr. 340/224 X 3,629,837 12/1971 Fraunfelder340/171 3,694,579 9/1972 McMurray. 179/5 R 3,713,125 l/l973 Miller340/224 Primary Examiner Donald J. Yusko Attorney, Agent, or FirmAnth0nyA. OBrien [57] ABSTRACT A radio warning. system includes emergencycondition sensors for actuating respective radio transmitters which aremodulated by identification generators to produce identification signalswhich contain one or more frequencies selected from groups of fourfrequencies in accordance with selected identifying binary coded decimaldigits. A transmitted identification signal is detected by a radioreceiver in a mobile unit or central dispatch location to operate amemory and a decimal display unit to indicate the existence and locationof the emergency condition until reset by an operator. The transmittersare deactuated by a timing circuit after a predetermined period. Delaycircuitry prevents operation of the memory and decimal display unituntil the identificationsignal has been received for a predeterminedcontinuous duration.

16 Claims, 9 Drawing Figures DlSPATCHER PATENTEDFEB 419?? SHEEI 10F 5f/az CIUME DVSPATCHER Pusuc HEALTH EMERGENCY D \STRESS \NDUSTR\ALMON\TOR\NG OTHER PATENTEDFE'B M915 SHEET Q 0F 5 Y I I I I I I I I IllOOOv I v EMERGENCY RADIO WARNING SYSTEM BAC KGROUND THE INVENTION l.Field of the Invention The present invention relates to emergencywarning systems which are used to detect and warn appropriateauthorities or personnel of emergency conditions such as crime, fire,pollution. or failure of critical equipment. This invention particularlyconcerns a remote emergency warning system which utilizes radio signalsto indicate the existence and location of an emergency condition.

2. Description of the Prior Art Present warning systems for alerting lawenforcement personnel or police of a crime involve the use of atelephone system to call and alert the police department. The policedepartment then contacts the nearest patrol car through the use of aradio communication system by a dispatcher. This procedure involves muchtime, with to minutes being typical in some cases, from the moment theemergency occurs to the moment that -help is dispatched. Certain systemsthat automatically call the police department are being banned in manymunicipalities due to the fact that they tend to jam telephoneswitchboards and cause confusion. Further, the automatic calling systemsare not under the direct control of the law enforcement agency, butrepresent systems and devices installed byindividuals or companies usingvery unreliable alarm systems, prone to false alarms.

In addition to the warning systems using the telephone system, there area number of prior art warning systems which utilize radio waves.Examples of prior art warning or communication systems which utilizeradio signals are described .in US. Pat.- No. 3,581,208, No. 3,618,067,and No. 3,629,837. The prior art radio warning systems generally haveone or more deficiencies, such as being subject to noise and interferingsignals, being complex and expensive, interfering with other use of thefrequency channels, etc.

SUMMARY OF THE INVENTION An object of the present'invention is a new andimproved radio warning system utilizing identification modulationsignals for readily identifying the location of an emergency condition.

A further object of the invention is a new and improved sensing andtransmitting system for generating a radio signal modulated byidentification signals for warning and identifying the location of anemergency condition.

A still further object of the invention is a new and improved receivingand displaying system for sensing an identification modulated radiosignal and for indicating the location of'an emergency condition.

In accordance with these and other objects, an embodiment of theinvention includes an emergency condition sensor operating a radiotransmitter modulated by an indentification signal generator whichproduces one or more frequencies selected from a group of fourfrequencies in accordance with an identifying binary coded decimaldigit. A radio receiver detects the indentification signal and operatesa decimal display in accordance with the frequencies in theindentification signal to indicate the location of the emergencycondition.

Further, a sensing and transmittingsystem includes facilities forterminating the operation of the transmitter after a predeterminedperiod.

A receiving and display system for a radio warning signal containingselected frequencies in accordance with an identifying binary codeddecimal digit includes facilities for detecting the binary coded decimaldigit and operating a decimal display to indicate the decimal digit.Further, the receiving and display system includes a memory foroperating the decimal display after the radio warning signal has beenterminated. Still further. the receiving and display system has delayfacilities for preventing operation of the decimal display until theidentifying signal has been received for a predetermined continuousduration.

Other objects and advantages of the present invention will becomeapparent from the following description taken in conjunction with theaccompanying drawrngs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating theutilization of a radio warning system in accordance with the invention;

FIG. 2 is a block diagram of a sensing and transmitting system forproducing radio signals modulated by one or more frequencies selectedfrom a group of four frequencies in accordance with an identifyingbinary coded decimal digit;

FIG. 3 is a block diagram of a receiving and displaying system fordetecting the signals from the system of FIG. 2 and displaying theindentifying decimal digit;

FIG. 4 is a detailed circuit diagram of arming and timing circuits inthe system shown in FIG. 2;

FIG. 5 is a detailed circuit diagram showing an identification generatorfor producing identifying modulation signals-in the system shown in FIG.2;

FIG. 6 is a detailed diagram of a circuit for detecting anidentification signal in the receiving and displaying system shown inFIG. 3;

FIG. 7 is a detailed diagram of a memory, driving and displayingcircuits in the receiving and displaying system shown in FIG. 3',

FIG. 8 shows a timing circuit for delaying the operation of thedisplaying circuit .of FIGS. 3 and 7 and for terminating the operationof a radio receiver of FIG. 3; and

FIG. 9 illustrates the allocation of identification numbers fordifferent uses in a radio warning system.

DESCRIPTION OF THE PREFERRED EMBODIMENT As is illustrated in FIG. 1, asensing and transmitting unit 10 produces a radio signal in response toan emergency condition. The radio signal produced by the unit 10 ismodulated by one or more frequencies which are selected from groups offour frequencies in accordance with a binary coded decimal (BCD) numberwhich identifies the location and/or nature of the emergency condition.Receiving and detecting units llll are located in a central dispatchstation 12, a vehicle 13 and/or a helicopter 14. The receivers llll mayshare antennas and radio frequency amplifying and detecting functionswith the normal transceiver units used for communication by usingdirectional couplers and other appropriate circuitry. Each of thereceivers ll-ll detect the indentification frequencies and operaterespective decimal displays 1S-15 to show the decimal number and thusindicate the location of the emergency condition.

Referring next to FIG. 2 there is shown a block diagram of transmittingcircuitry in the unit which is actuated by the operation of a sensor 17.The sensor 17 may be any electronic device which can be used to detect acondition. For example, the sensor 17 may be a switch device operated by(l) a teller in a bank, (2) the breaking ofa window, (3) excessive heat,(4) pollution or (5) failure of critical equipment. An arming circuit 18is triggered and latched by the operation of the sensor 17 to initiateoperation of a radio frequency (RF) transmitter 19 and a BCDidentification signal generator 20 to transmit radio warning signalsfrom an an tenna 21. The BCD generator 20 applies the identificationsignal to the audio or modulation input of the transmitter 19. A timingcircuit 22 is also activated by the arming circuit 18 to disable thearming circuit 18 and terminate operation of the RF transmitter 19 andBCD generator 20 after a predetermined period of op eration. The periodis selected to avoid unduly interfering with other use of the RFfrequency channel. The arming circuit 18 remains latched and disableduntil reset by an operator, such as a police officer, momentarilyopening a switch 23 to interrupt current from a battery 24 which ischarged by a charger 25. A lamp 26 indicates that the arming circuit 18has been actuated and latched. A lamp 27 indicates that the RFtransmitter 19 and BCD generator 20 are operating. The arming circuit 18and the timing circuit 22 are more fully described hereinafter under theheading Arming Circuit and Transmitter Timing Circuit. The BCD generator20 is more fully described hereinafter under the heading BCD Generator.The RF transmitter 19 may be any suitable commercially available radiotransmitter which can operate at a selected radio frequency under theappropriate government regulations. A frequency modulated transmitter ispreferred, but a suitable amplitude modulated transmitter may alsobeemployed. It is contemplated that the identification signals from theBCD generator 20 contain frequencies in the audio range, however,frequencies not within the audio range may be used where a suitable RFtransmitter is employed.

A block diagram of circuitry for receiving, detecting and displaying awarning signal generated by the transmitting circuitry of FIG. 2 isshown in FIG. 3. The radio warning signal is received by an RF receiver32 from an antenna 31. The RF receiver 32 may be any radio receiver, orchannel in a multichannel receiver, which is tuned to the radiofrequency transmitted by the warning transmitters 19 of FIG. 2. Thereceiver 32 detects the indentification signal and applies it to theinput of a BCD frequency detector 33. The BCD detector 33 produces anoutput corresponding to a first binary coded decimal digit in theindentification signal after the identification signal has been receivedfor a predetermined continuous duration. The first binary coded decimaldigit is applied to a memory circuit 34 and a ceiver 32 and to enablethe driving circuits 35 and 35a 4 and the displays 36 and 36a after apredetermined de- 1 lay. Also, an audio alarm 38 is actuated by thetiming circuit 37 after the predetermined delay. The duration of delayby the timing circuit 37 insures that the identification signal isdetected and applied to the memories 34 and 34a prior to disablement ofthe receiver 32 and operation of the displays 36 and 36a. The displays36 and 36a and the audio alarm 38 remain activated until current from abattery 39 is momentarily interrupted by the opening of a manual resetswitch 40. The BCD detector 33 is more fully described hereinafter underthe heading BCD Detector". The memory circuit 34. driving circuit 35 anddisplay 36 are more fully described hereinafter under the headingMemory, Driver, and Display". The timing circuit 37 is more fullydescribed hereinafter under the heading Receiver Timing Circuit".

ARMING AND TIMING CIRCUITS The arming circuit 18 is shown in detail inFIG. 4. The operation of the sensor 17 by an emergency condition appliesa triggering signal to a voltage divider consisting of resistors 42 and43 and thus to a control electrode of a silicon controlled rectifier(SCR) 44. The SCR is connected in series with a resistor 45 and thebattery 24 so that a voltage is produced across the resistor 45 when theSCR 44 is triggered into conduction. The voltage on the resistor 45 isapplied by a resistor 47 to the base of a transistor 48 to render thetransistor 48 conductive. The transistor 48 is connected in series withthe battery 24 and a coil 49 of .a relay 50. When the coil 49 isenergized by conduction of thetransistor 48, contacts 51 of the relayare closed to apply an energizing voltage from the battery 24 to aterminal 53 which energizes the RF transmitter 19, BCD generator 20 andlamp 27 of FIG. 2. Also, the voltage across the resistor 45 is appliedby a resistor 54 to a base ofa transistor 55 connected in series withthe battery 24 and the lamp 26 to render the transistor 55 conductiveand energize the lamp 26. The SCR 44 and the lamp 26 remain activateduntil the arming circuit is manually reset by the momentary opening ofthe reset switch 23 which interrupts the current from the battery 24.

The timing circuit 22 is also energized by the voltage produced acrossthe resistor 45. Current through a variable resistor 57 charges acapacitor 58 to trigger a unijunction transistor 59 connected in serieswith a resistor 60 across the resistor 45 after a predetermined delay.When the unijunction 59 is triggered, the increase in voltage across theresistor 60 produces a pulse through a capacitor 62 connected to acontrol electrode of a SCR 63. The SCR 63, when triggered by the pulsethrough capacitor 62, connects the base of the transistor 48 to areverse bias potential or ground to render the transistor 48non-conductive. This deenergizes the relay 50 to terminate operation ofthe RF transmitter 19, the BCD generator 20 and the lamp 27 of FIG. 2. Adiode 64 connected across the coil 49 provides a bypass for inducedcurrent when transistor 48 is rendered non-conductive. The values of thecapacitor 58 and the variable resistor 57 are selected to produce thepredetermined period of operation of the transmitter 19 and BCDgenerator 20. The SCR 63 is delatched when the reset switch 23 isopened.

BCD GENERATOR Referring to FIG. 5 there is shown a circuit diagram of asingle digit BCD generator 20 which is energized by the application of avoltage to terminal 53 by the arming circuit 18 of FIG. 4. Inverteramplifiers 66-69 with positive feedback through respective filters 71-74and resistors 76-79 operate as individual oscillators producingfrequencies F1, F2, F3, and F4. As shown the inverter amplifiers 66-69may be a Quad NAND gate package 80, energized by the application of thevoltage to terminal 53, with the inputs of each gate connected together.The RCA CD 401IAE has been found to work well in this circuit. Thefilters 71-74 are preferably a narrow bandwidth type, such as miniaturepiezoelectric coupled tuning fork filters for audio signalling. seriesEMR-S manufactured by the MURATA Corporation of America. High Frequencydecoupling capacitors 81-84 prevent the oscillators from producinghigher than audio frequencies. Capacitors 86-89 couple the outputs ofthe amplifiers 66-69 to a terminal 70 connected to the audio input ofthe RF transmitter of FIG. 2.

The oscillators are selectively disabled to produce only one or more ofthe frequencies F1, F2, F3, and F4 in accordance with a selected binarycoded decimal digit which identifies the transmitter and the location ofthe emergency condition. The BCD generator shown in FIG. 5 generates anidentification signal which contains simultaneously generatedfrequencies in accordance with a single binary coded decimal digit. Ifan identification signal is to include two or more binary coded decimaldigits, additional oscillator circuits substantially similar to that ofFIG. 5 are added. The additional circuits would produce additionalgroups of frequencies which are different from the group of frequenciesFl-F4 but simultaneously generated with frequencies Fl-F4. For example,100 indentifying decimal digits through 99 may be provided by using twogroups of four frequencies Fl-F4 and F-F8.

BCD DETECTOR FIG. 6 shows in detail the BCD detector circuit 33 of thecircuit shown in FIG. 3. The audio output of the RF receiver 32 isapplied in parallel to filters 91-94. The filters 91-94 are selected topass the respective frequencies F1-F4. The filters 91-94, like thefilters 71-74 of FIG. 5, are preferable narrow bandpass type filters,such as miniature piezoelectric coupled tuning fork filters, to preventerroneous operation by noise and voice signals. The outputs of thefilters 91-94 are amplified by the amplifiers 96-99 which are biasedlinearly by respective resistors 101-104. Like the amplifiers 66-69 ofFIG. 5, the amplifiers 96-99 may be a Quad NAND gate package 100 withthe inputs of each gate connected together.

The outputs of the amplifiers 96-99 are applied to respective voltagerectifying and doubling circuits including capacitors 106-109, diodes111-114 and 116-119, capacitors l2l-l24'and resistors 126-129. Duringnegative half cycles of the identifying signals from the amplifiers96-99, the respective capacitors 106-109 are charged by current throughthe diodes 111-114. During positive half cycles of the identifyingsignals, the diodes 116-119 conduct to transfer the charges on therespective capacitor 106-109 to the capacitors 121-124 and produceoutput voltages on terminals 131-134 which are about double the maximumamplitudes of the respective identifying signals. The resistors 126-129provide loads for the diodes 116-119.

The capacitors 121-124 are relatively large D.C. filtering capacitorswhile the capacitors 106-109 are relatively small coupling capacitors.This produces a delay in the voltage on the terminals 131-134 reachingmaximum amplitudes. This delay is selected, taking into considerationthe bandpass of the filters 71-74, to prevent the operation of thememory circuit 34 of FIG. 3 until the one or more of signals F1-F4 havebeen present for a predetermined continuous duration to prevent spuriousnoise signals or voice signals from erroneously actuating the memorycircuit 34. The selection of the values of the components in therectifying and doubling circuits is made to produce the predetermineddelay taking into consideration the different frequencies of operation.

The BCD detector circuit of FIG. 6 will only detect one binary codeddecimal digit. Additional circuits substantially similar to FIG. 6 areused to sense additional digits in an indentification signal. Forexample. one additional circuit which senses frequencies F5, F6, F7, andF8 would provide for the detection of I00 decimal numbers 00 through 99.

MEMORY, DRIVER AND DISPLAY Referring to FIG. 7 there is shown in detailthe memory circuit 34, display driving circuit 35, and the decimaldisplay 36. The outputs of the BCD detector 33 on terminals 131-134 areapplied by respective diodes 136-139 to control electrodes of SCRs141-144. If a sufficiently large signal is present on any of theterminals 131-134, the respective SCR is triggered to produce a voltageacross a respective resistor 146-149. The SCRs 141-144 remain activatedto retain the binary coded decimal digit until the circuit is reset byinterruption of voltage on a terminal 150. The voltage or voltagesacross the resistors 146-149 are applied to terminals 151-154 of thedisplay driving circuit 35 which operates the decimal display 36. Thedriving circuit 35 is selected to produce appropriate energizingvoltages for the particular decimal display in response to a binarycoded decimal digit input. For example, the display 36 may be a sevenelement type, such as RCA model DR 2000. RCA CD 2500E may be used todrive the RCA display. A switch 155 is provided for testing the display36.

As previously explained, the driving circuit 35 and display 36 areprevented by the timing circuit 37 (FIG. 3) from operating for apredetermined duration after the memory 33 has received a binary digit.Diodes 156-159 are connected to the resistors 146-149 in an OR gatearrangement to apply a signal to terminal 160 when any of the SCRs141-144 are actuated. This operates the timing circuit 37 (FIG. 3)which, after the predetermined duration, applies an operating voltage toa terminal 177. A transistor 181 connected between the terminal 177 andthe power inputs of the driving circuit 35 and the display 36 iscontrolled by a zener diode 182 and bias resistor 183 to provide aregulated voltage to the driving circuit 35 and the display 36.

RECEIVER TIMING CIRCUIT Referring to FIG. 8 there is shown the timingcircuit 37 for disabling the RF receiver 32 of FIG. 2 and enabling thedriving circuit 35 and display 36. When a bi- 162 has sufficientlycharged, a unijunction transistor 163 is operated to produce a voltageacross a resistor 165. A capacitor 167 connected to the resistor 165applies a pulse to a control electrode of an SCR 166 which is connectedin series with the battery 39 and a coil 168 ofa relay 169. Before thecoil 168 is energized, a contact arm 171 engages a contact 172 to applyvoltage from the battery 39 to a terminal 178 and filtering capacitor179. The terminal 178 supplies voltage to the RF receiver 32. After thecoil 168 has been energized by the conduction of SCR 166. the contactarm 171 disengages the contact 172 and engages a contact 173 to apply avoltage from the battery 39 to the terminal 177 and the audible alarm38. Thus, the RF receiver 32 is disabled and the driving circuit 35 anddisplay 36 are enabled. The delay of the timing circuit 37 is selectedto be greater than any difference in the delays of any two of theoutputs of the BCD detector 33 so that the display 36 will indicate thecorrect identification digit. The alarm 38 and the display 36 remainactivated until the reset switch 40 is manually opened to interrupt thecurrent to the SCR 166 and the SCR's 141-144 (FIG. 7) in the memory 33.

OPERATION In operation of the radio warning system, sensing andtransmitting units 10 (FIG. 1) are placed in locations where it isdesired to monitor or sense a condition which may require immediateattention. When such a condition occurs, the respective sensing andtransmitting unit 10 transmits a radio signal modulated by one or morefrequencies selected from one or more groups of four frequencies inaccordance with one or more identifying binary coded decimal digits. Oneor more receiving units 11-11 in the central dispatch station 12,automobile 13 and helicopter 14 receive the radio warning signal anddisplay the identification decimal digit or digits on displays 15l5 andoperate audible alarms 38 (FIGS. 3 and 8). The appropriate authority,such as a police officer, may immediately respond and take theappropriate action to overcome or meet the emergency condition.

It is contemplated that the system of the invention be under the'control of an appropriate governmental agency, such as the police. Thelocations to be monitored can thus be selected and limited to readilycover the areas of greatest need within the capabilities of theavailable personnel. Also the quality of the sensing and transmittingunits may be readily controlled and maintained to produce a highstandard of service.

The identifying modulation signals for one binary coded digit areproduced by the oscillator amplifiers 66-69 shown in FIG. 5. To selectthe frequencies in accordance with the identifying binary coded decimaldigit, the oscillating circuits are selectively disabled by opencircuiting the inputs or outputs of selected amplitiers 66-69 oreliminating or disconnecting selected filters 71-41, resistors 76-79 orcapacitors 86-89. Thus, the modulation signal contains one or moresimultaneously generated frequencies selected from the group offrequencies F1-F4. For additional identifying decimal digits, additionaloscillator circuits may be added to supply additional groups of fourfrequencies. The use ofidentification frequencies selected in accordancewith indentifying binary coded decimal digits allows the use ofinexpensive conventional binary coded decimal circuits.

In TABLE I, there are illustrated two schemes for selecting frequenciesF1, F2, F3, and F4 in accordance with a binary coded decimal digit. Thethird column lists a selection of frequencies made in accordance withbinary coded decimal digits listed in the second column which correspondto the respective decimal digits in the first column. The fourth columnis the inverse of the second column while the fifth column illustrates aselection of frequencies in accordance with the inverted binary codeddecimal digits. Other conventional binary coding schemes and frequencyselection may be used so long as they are readily employable withavailable decimal circuitry.

One of the advantages of the invention is the large number ofidentifying numbers which are available for a relatively few modulationfrequencies. Four frequencies provide 10 identifying digits, eightfrequencies provide identifying digits, 12 frequencies provide 1,000identifying digits. etc. This allows flexibility in the employment of aradio warning system with a minimum use of a radio frequency channel.

In FIG. 9 there is illustrated an allocation of the identifying numbersfor a variety of uses. The numbers may be allocated for use in(1)sensing crime, such as burglary, robbery. etc.; (2) sensing a fire orfire alarm; (3) sensing other matters concerning public health andsafety, such as air or water pollution, etc.', (4) sensing an emergencydistress, such as a need for service on a highway; and (5) sensingindustrial equipment failure. The allocation of the identifying numbersand use of the system may be under the control of a local governmentalorganization, such as a police department, thus enabling optimum usageof the system.

After a predetermined period of operation, the transmission of a radiowarning signal is terminated by the operation of the unijunctiontransistor 59 (FIG. 4) which fires the SCR 63 to render the transistor48 nonconductive and open the relay 50 to disrupt power to thetransmitter 19 and BCD generator 20. This prevents the transmitting unitfrom unduly interfering with other use of the radio frequency channel.The period of operation may be selected by adjusting the variableresistor 57. Typically, the period may be selected from the range of 10to 100 seconds, but periods outside this range may be readily used.

Once the sensor 17 (FIGS. 2 and 4) has triggered and latched the armingcircuit 18, the lamps 26 and 27 are energized. The lamp 27 remainsenergized only during the operation of the transmitter 19 and BCDgenerator 20. The lamp 26 remains energized until the arming circuit 18is delatched by manually opening the reset switch 23.

The radio frequency warning signal is received by the RF receiver 32(FIG. 3) which detects and produces the identifying signal. Thereceiving and displaying system may be readily employed withconventional radio communication equipment used by commercialestablishments or governmental authorities, such as the police. Theradio receiver 32 and the antenna 31 may be part of their normalcommunication equipment.

The frequencies in the identification signal are sensed by the filters91-94 (FIG. 6) and applied to rectifying and doubling circuits. The useof narrow bandpass filters helps prevent interference from noise andspurious signals or ordinary communication in the operation of thewarning system. Also, the delays caused by the capacitors 106-109 and121-124, diodes 111-114 and 116-119, and resistors 126-129 in therectifying and doubling circuits insure that the identifcation signalshave been present for a predetermined continuous duration and helpprevent interference from erroneously operating the SCRs 141-144 (FIG.7) in the memory 34 or 3411. A range of delays from V2 to I second isacceptable but durations of delays outside that range may produceequally acceptable results. Once a binary digit or digits have beenreceived by the memories 34 and 340, the timing circuit 37 (FIG. 8) isoperated after a predetermined delay to disable the RF receiver 32 andto enable the driving circuits 35 and 35a, the'displays 36 and 36a andthe alarm 38. The delay of the timing circuit 37 allows for differencesin the delays of the rectifying and doubling circuits of the BCDdetector 33 to insure that all the binary digits of the binary codeddecimal digit or digits have been received by the memories 34 and 34a.After the operation of the timing circuit 37, the identifying decimaldigit or digits remain displayed on the displays 34 and 34a and thealarm 38 remains actuated until an operator resets the timing circuit 36by momentarily opening the switch 40.

Inasmuch as the present invention is subject to many variations,modifications and changes in detail, it is intended that all mattercontained in the foregoing description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:

1. An emergency radio warning system comprising:

a sensor operable upon an emergency condition;

means operated by the sensor in response to an emergency condition forgenerating and transmitting a radio signal having apredeterminedfrequency;

means for modulating the generating and transmitting means with anidentification signal having one or more simultaneously generatedfrequencies selected from a group of four frequencies in accordance withan identifying binary coded decimal digit;

said modulating means including one or more oscillator circuits, eachhaving in circuit a tuning fork filter resonant at a respective selectedfrequency;

means for receiving the modulated radio signal and detecting theidentification signal;

said receiving and detecting means including four tuning fork filtersresonant at the respective four frequencies; and

means responsive to the identification signal for displaying the decimaldigit corresponding to the detected identification signal to indicatethe location of the emergency condition.

. 10 2. A system as defined in claim 1wherein said receiving anddetecting'means includes delay means for preventing the operation of thedisplaying means for a predetermined continuous duration of the presenceof an identification signal.

3. An emergency radio warning system comprising:

a sensor operable upon an emergency condition;

means operated by the sensor in response to an emergency condition forgenerating and transmitting a radio signal having a predeterminedfrequency;

means for modulating the generating and transmitting means with anidentification signal having one or more simultaneously generatedfrequencies selected from a group of four frequencies in accordance withan identifying binary coded decimal digit;

timing means for terminating the operation of the generating andtransmitting means a predetermined duration after initiation of theoperation of the generating and transmitting means;

means for receiving the modulated radio signal and detecting theidentification signal;

said receiving and detecting means including four filter means fordetecting the respective four frequencies, each of said four filtermeans being nonresponsive to signals of less than a predeterminedcontinuous duration;

memory means actuated by the identification signal for producing outputsignals corresponding to the identifying binarycoded decimal digit untilreset by an operator; and

means responsive to the output signals of the memory means fordisplaying the decimal digit corresponding to the identifying binarycoded decimal digit to indicate the location of the emergency condition.

4. A system as defined in claim 3 which includes:

an arming circuit interposed between the sensor and the generating andtransmitting means, said arming circuit including means for latching inresponse to the operation of the sensor to operate the generating andtransmitting means;

means between the latching means and the transmitting means, operated bythe timing means, for terminating the operation of the generating andtransmitting means;

means for resetting the latching means; and

means for indicating the latched condition of the arming circuit.

5. A system as defined in claim 3 wherein:

each of the four filter means includes a tuning fork filter and delaymeans responsive to the output of a respective filter for producing arespective delayed signal after at least a predetermined continuousduration of the presence of an identification signal; and

the memory means includes four binary memory means each responsive to arespective delayed signal for producing an output signal.

6. An emergency radio warning system comprising a sensor operable uponan emergency condition;

means operated by the sensor in response to an emergency condition forgenerating and transmitting a radio signal having a predeterminedfrequency;

means for modulating the generating and transmitting means with anidentification signal having one or more frequencies selected from agroup of four 1 l frequencies in accordance with an identifying binarycoded decimal digit;

means for receiving the modulated radiovsignal and detecting theidentification signal;

said receiving and detecting means including four filter means fordetecting the respective four frequencies, each of said four filtermeansbeing nonresponsive to signals of less than a predeterminedcontinuous duration;

memory means actuated by the identification signal for producing outputsignals corresponding to the identifying binary coded decimal digituntil reset by an operator;

means responsive to the output signals of the memory means fordisplaying the decimal digit corresponding to the identifying binarycoded decimal digit to indicate the location of the emergency condition;

a relay having normally open contacts for applying voltage from a sourceto the generating and transmitting means when a coil of the relay isenergized;

a transistor having an emitter and collector connected in series withthe coil and the source;

a resistor;

a first silicon controlled rectifier having its anode and cathodeconnected in series with the resistor and the source;

means connecting the sensor to a control electrode of the first siliconcontrolled rectifier for initiating conduction through the first siliconcontrolled rec tifier in response to an emergency condition;

means connected across the resistor for biasing the base of thetransistor into conduction in response to the conduction of the firstsilicon controlled rectifier to operate the generating and transmittingmeans;

a unijunction transistor timing circuit connected across the resistor;

a second silicon controlled rectifier having its anode and cathodeconnected between the base of the transistor and a reverse biaspotential;

means connecting the unijunction transistor timing circuit to a controlelectrode of the second silicon controlled rectifier for terminatingconduction of a the transistor to terminate the operation of thegenerating and transmitting means; and

means actuated by an operator for momentarily interrupting the source.

7. An emergency radio warning system comprising a sensor operable uponan emergency condition;

means operated by the sensor in response to an emergency condition forgenerating and transmitting a radio signal having a predeterminedfrequency;

means for modulating the generating and transmitting means with anidentification signal having one or more frequencies selected from agroup of four frequencies in accordance with an identifying binary codeddecimal digit;

timing means for terminating the operation of the generating andtransmitting means a predetermined duration after initiation of theoperation of xthe generating and transmitting means;

means for receiving the modulated radio signal and detecting theidentification signal;

said receiving and detecting means including four filter means fordetecting the respective four frequencies, each of said four filtermeans being nonresponsive to signals of less than a predeterminedcontinuous duration;

each of the four filter means including a tuning fork filter and delaymeans responsive to the output of a respective filter forproducing arespective delayed signal after at least a predetermined continuousduration of the presence of an identification signal;

memory means actuated by the identification signal for producing outputsignals corresponding to the identifying binary, coded decimal digituntil reset by an operator;

said memory means including four binary memory means each responsive toa respective delayed signal for producing an output signal;

means responsive to the output signals of the memory means fordisplaying the decimal digit corresponding to the identifying binarycoded decimal digit to indicate the location of the emergency condition;and

timing means responsive to the operation of a binary memory means fordisabling the receiving and detecting means and for enabling theoperation of the displaying means after the periods of operation of allthe four delay means.

8. A system as defined in claim 7 wherein the timing means for disablingthe receiving and detecting means and for enabling the displaying meansincludes:

a unijunction transistor timing circuit having a predetermined delaywhich is greater than the difference between the delays of any two ofthe four delay means;

means for sensing the operation of memory means to operate theunijunction timing circuit;

a relay having a contact arm for normally engaging a first contact, saidcontact arm disengaging the first contact and engaging a second contactwhen a coil of the relay is energized, said contact arm connected to avoltage source, said first contact connected to the receiving anddetecting means, said second contact connected to the displaying means;

a silicon controlled rectifier having its anode and cathode in serieswith the coil; and

means connecting an output of the unijunction transistor timing circuitto a control electrode of the silicon controlled rectifier forenergizing the coil after the predetermined delay of the transistortiming circuit to disable the receiving and detecting means and forenabling the displaying means.

9. A sensing and transmitting system for generating a radio signalmodulated by identification signals for identifying the location of anemergency condition comprising:

a sensor-operable upon an emergency condition;

means operated by the sensor in response to an emergency condition forgenerating and transmitting a radio signal having a predeterminedfrequency;

means for modulating the generating and transmitting meanswith anidentification signal having one or more simultaneously generatedfrequencies selected from a group of four frequencies in accordance withan identifying binary coded decimal said modulating means including oneor more oscillator circuits each having in circuit a tuning fork filterresonant at a respective selected frequency; and

timing means for terminating the operation of the generating andtransmitting means a predetermined duration after initiation of theoperation of the generating and transmitting means.

10. A system as defined in claim 9 which includes:

an arming circuit interposed between the sensor and the generating andtransmitting means,

said arming circuit including means for latching in response to theoperation of the sensor to operate the generating and transmitting meansand to operate the timing means;

manual means for resetting the latching means; and

means for indicating the latched condition of the arming circuit.

11. A sensing and transmitting system for generating a radio signalmodulated by identification signals for identifying the location of anemergency condition, comprising:

a sensor operable upon an emergency condition;

means operated by the sensor in response to an emergency condition forgenerating and transmitting a radio signal having a predeterminedfrequency;

means for modulating the generating and transmitting means with anidentification signal having one or more frequencies selected from agroup of four frequencies in accordance with an identifying binary codeddecimal digit;

said modulating means including one or more oscillator circuits eachhaving in circuit a tuning fork filter resonant at a respective selectedfrequency;

a relay having normally open contacts for applying voltage from a sourceto the generating and transmitting means when a coil of the relay isenergized;

a transistor having an emitter and collector connected in series withthe coil and the source;

a resistor;

a first silicon controlled rectifier having its anode and cathodeconnected in series with the resistor and the source;

means connecting the sensor to a control electrode of the first siliconcontrolled rectifier for initiating conduction through the first siliconcontrolled rectifier in response to an emergency condition;

means connected across the resistor for biasing the base of thetransistor into conduction in response to the conduction of the firstsilicon controlled rectifier to operate the generating and transmittingmeans; V

a unijunction transistor timing circuit connected across the resistor;

a second silicon controlled rectifier having its anode and cathodeconnected between the base of the transistor and a reverse biaspotential;

means connecting the unijunction transistor timing circuit to a controlelectrode of the second silicon controlledrectifier for terminatingconduction of the transistor to terminate the operation of thegenerating and transmittingmeans; and

means actuated by an operator for momentarily interrupting the source.

12. A receiving and displaying system which senses and displays anidentifying decimal digit from a radio signal which is modulated by anidentification signal containing one or more frequencies selected from agroup of four frequencies in accordance with a binary coded decimaldigit which corresponds to the identifying decimal digit to indicate thelocation of an emergency condition, comprising means for receiving themodulated radio signal and detecting the identification signal;

four filter means responsive to the respective four frequencies in theidentification signal for producing parallel signals corresponding tothe binary coded decimal digit;

each of said four filter means being non-responsive to signals of lessthan a predetermined continuous duration;

means responsive to the signals produced by the four filter means fordisplaying the identifying decimal digit to indicate the location of theemergency condition;

four memory means actuated by the respective signals from the fourfilter means for continuing the operation of the displaying means todisplay the decimal digit after the termination of the radio signaluntil reset by an operator; and

timing means responsive to the operation of a memory means for disablingthe receiving and detecting means and for enabling the operation of thedisplaying means after the periods of operation of all the four delaymeans.

13. A system as defined in claim 12 wherein the timing means fordisabling the receiving and detecting means and for enabling thedisplaying means includes:

a unijunction transistor timing circuit having a predetermined delaywhich is greater than the difference between the delays of any two ofthe four delay means;

means responsive to the actuating of any of the four memory means foroperating the unijunction timing circuit;

a relay having a contact arm for normally engaging a first contact, saidcontact arm disengaging the first contact and engaging a second contactwhen a coil of the relay is energized, said contact arm connected to avoltage source, said first contact connected to the receiving anddetecting means, said second contact connected'to the displaying means;

a silicon controlled rectifier having its anode and cathode in serieswith the coil; and

means connecting an output of the unijunction transistor timing circuitto a control electrode of the silicon controlled rectifier forenergizing the coil after the predetermined delay of the transistortiming circuit todisable the receiving and detecting means and to enablethe displaying means.

14. A system as defined in claim 12 which includes:

four memory means actuated by the respective signals from the fourfilter means for continuing the operation of the displaying means todisplay the decimal digit after the termination of the radio signaluntil reset by an operator.

15. A system as defined in claim 12 wherein each of the four filtermeans includes:

a tuning fork filter, and

a delay means between the respective filter and the displaying means forpreventing the operation of the displaying means for a predeterminedcontinuous duration of the presence of an identification signal.

16. A system as defined in claim 12 wherein each of the four filtermeans includes a tuning fork filter.

1. An emergency radio warning system comprising: a sensor operable uponan emergency condition; means operated by the sensor in response to anemergency condition for generating and transmitting a radio signalhaving a predetermined frequency; means for modulating the generatingand transmitting means with an identification signal having one or moresimultaneously generated frequencies selected from a group of fourfrequencies in accordance with an identifying binary coded decimaldigit; said modulating means including one or more oscillator circuits,each having in circuit a tuning fork filter resonant at a respectiveselected frequency; means for receiving the modulAted radio signal anddetecting the identification signal; said receiving and detecting meansincluding four tuning fork filters resonant at the respective fourfrequencies; and means responsive to the identification signal fordisplaying the decimal digit corresponding to the detectedidentification signal to indicate the location of the emergencycondition.
 2. A system as defined in claim 1 wherein said receiving anddetecting means includes delay means for preventing the operation of thedisplaying means for a predetermined continuous duration of the presenceof an identification signal.
 3. An emergency radio warning systemcomprising: a sensor operable upon an emergency condition; meansoperated by the sensor in response to an emergency condition forgenerating and transmitting a radio signal having a predeterminedfrequency; means for modulating the generating and transmitting meanswith an identification signal having one or more simultaneouslygenerated frequencies selected from a group of four frequencies inaccordance with an identifying binary coded decimal digit; timing meansfor terminating the operation of the generating and transmitting means apredetermined duration after initiation of the operation of thegenerating and transmitting means; means for receiving the modulatedradio signal and detecting the identification signal; said receiving anddetecting means including four filter means for detecting the respectivefour frequencies, each of said four filter means being non-responsive tosignals of less than a predetermined continuous duration; memory meansactuated by the identification signal for producing output signalscorresponding to the identifying binary coded decimal digit until resetby an operator; and means responsive to the output signals of the memorymeans for displaying the decimal digit corresponding to the identifyingbinary coded decimal digit to indicate the location of the emergencycondition.
 4. A system as defined in claim 3 which includes: an armingcircuit interposed between the sensor and the generating andtransmitting means, said arming circuit including means for latching inresponse to the operation of the sensor to operate the generating andtransmitting means; means between the latching means and thetransmitting means, operated by the timing means, for terminating theoperation of the generating and transmitting means; means for resettingthe latching means; and means for indicating the latched condition ofthe arming circuit.
 5. A system as defined in claim 3 wherein: each ofthe four filter means includes a tuning fork filter and delay meansresponsive to the output of a respective filter for producing arespective delayed signal after at least a predetermined continuousduration of the presence of an identification signal; and the memorymeans includes four binary memory means each responsive to a respectivedelayed signal for producing an output signal.
 6. An emergency radiowarning system comprising a sensor operable upon an emergency condition;means operated by the sensor in response to an emergency condition forgenerating and transmitting a radio signal having a predeterminedfrequency; means for modulating the generating and transmitting meanswith an identification signal having one or more frequencies selectedfrom a group of four frequencies in accordance with an identifyingbinary coded decimal digit; means for receiving the modulated radiosignal and detecting the identification signal; said receiving anddetecting means including four filter means for detecting the respectivefour frequencies, each of said four filter means being non-responsive tosignals of less than a predetermined continuous duration; memory meansactuated by the identification signal for producing output signalscorresponding to the identifying binary coded decimal digit until resetby an operator; meAns responsive to the output signals of the memorymeans for displaying the decimal digit corresponding to the identifyingbinary coded decimal digit to indicate the location of the emergencycondition; a relay having normally open contacts for applying voltagefrom a source to the generating and transmitting means when a coil ofthe relay is energized; a transistor having an emitter and collectorconnected in series with the coil and the source; a resistor; a firstsilicon controlled rectifier having its anode and cathode connected inseries with the resistor and the source; means connecting the sensor toa control electrode of the first silicon controlled rectifier forinitiating conduction through the first silicon controlled rectifier inresponse to an emergency condition; means connected across the resistorfor biasing the base of the transistor into conduction in response tothe conduction of the first silicon controlled rectifier to operate thegenerating and transmitting means; a unijunction transistor timingcircuit connected across the resistor; a second silicon controlledrectifier having its anode and cathode connected between the base of thetransistor and a reverse bias potential; means connecting theunijunction transistor timing circuit to a control electrode of thesecond silicon controlled rectifier for terminating conduction of thetransistor to terminate the operation of the generating and transmittingmeans; and means actuated by an operator for momentarily interruptingthe source.
 7. An emergency radio warning system comprising a sensoroperable upon an emergency condition; means operated by the sensor inresponse to an emergency condition for generating and transmitting aradio signal having a predetermined frequency; means for modulating thegenerating and transmitting means with an identification signal havingone or more frequencies selected from a group of four frequencies inaccordance with an identifying binary coded decimal digit; timing meansfor terminating the operation of the generating and transmitting means apredetermined duration after initiation of the operation of thegenerating and transmitting means; means for receiving the modulatedradio signal and detecting the identification signal; said receiving anddetecting means including four filter means for detecting the respectivefour frequencies, each of said four filter means being non-responsive tosignals of less than a predetermined continuous duration; each of thefour filter means including a tuning fork filter and delay meansresponsive to the output of a respective filter for producing arespective delayed signal after at least a predetermined continuousduration of the presence of an identification signal; memory meansactuated by the identification signal for producing output signalscorresponding to the identifying binary coded decimal digit until resetby an operator; said memory means including four binary memory meanseach responsive to a respective delayed signal for producing an outputsignal; means responsive to the output signals of the memory means fordisplaying the decimal digit corresponding to the identifying binarycoded decimal digit to indicate the location of the emergency condition;and timing means responsive to the operation of a binary memory meansfor disabling the receiving and detecting means and for enabling theoperation of the displaying means after the periods of operation of allthe four delay means.
 8. A system as defined in claim 7 wherein thetiming means for disabling the receiving and detecting means and forenabling the displaying means includes: a unijunction transistor timingcircuit having a predetermined delay which is greater than thedifference between the delays of any two of the four delay means; meansfor sensing the operation of memory means to operate the unijunctiontiming circuit; a relay having a contacT arm for normally engaging afirst contact, said contact arm disengaging the first contact andengaging a second contact when a coil of the relay is energized, saidcontact arm connected to a voltage source, said first contact connectedto the receiving and detecting means, said second contact connected tothe displaying means; a silicon controlled rectifier having its anodeand cathode in series with the coil; and means connecting an output ofthe unijunction transistor timing circuit to a control electrode of thesilicon controlled rectifier for energizing the coil after thepredetermined delay of the transistor timing circuit to disable thereceiving and detecting means and for enabling the displaying means. 9.A sensing and transmitting system for generating a radio signalmodulated by identification signals for identifying the location of anemergency condition comprising: a sensor operable upon an emergencycondition; means operated by the sensor in response to an emergencycondition for generating and transmitting a radio signal having apredetermined frequency; means for modulating the generating andtransmitting means with an identification signal having one or moresimultaneously generated frequencies selected from a group of fourfrequencies in accordance with an identifying binary coded decimaldigit; said modulating means including one or more oscillator circuitseach having in circuit a tuning fork filter resonant at a respectiveselected frequency; and timing means for terminating the operation ofthe generating and transmitting means a predetermined duration afterinitiation of the operation of the generating and transmitting means.10. A system as defined in claim 9 which includes: an arming circuitinterposed between the sensor and the generating and transmitting means,said arming circuit including means for latching in response to theoperation of the sensor to operate the generating and transmitting meansand to operate the timing means; manual means for resetting the latchingmeans; and means for indicating the latched condition of the armingcircuit.
 11. A sensing and transmitting system for generating a radiosignal modulated by identification signals for identifying the locationof an emergency condition, comprising: a sensor operable upon anemergency condition; means operated by the sensor in response to anemergency condition for generating and transmitting a radio signalhaving a predetermined frequency; means for modulating the generatingand transmitting means with an identification signal having one or morefrequencies selected from a group of four frequencies in accordance withan identifying binary coded decimal digit; said modulating meansincluding one or more oscillator circuits each having in circuit atuning fork filter resonant at a respective selected frequency; a relayhaving normally open contacts for applying voltage from a source to thegenerating and transmitting means when a coil of the relay is energized;a transistor having an emitter and collector connected in series withthe coil and the source; a resistor; a first silicon controlledrectifier having its anode and cathode connected in series with theresistor and the source; means connecting the sensor to a controlelectrode of the first silicon controlled rectifier for initiatingconduction through the first silicon controlled rectifier in response toan emergency condition; means connected across the resistor for biasingthe base of the transistor into conduction in response to the conductionof the first silicon controlled rectifier to operate the generating andtransmitting means; a unijunction transistor timing circuit connectedacross the resistor; a second silicon controlled rectifier having itsanode and cathode connected between the base of the transistor and areverse bias potential; means connecting the unijunction transistortiming cirCuit to a control electrode of the second silicon controlledrectifier for terminating conduction of the transistor to terminate theoperation of the generating and transmitting means; and means actuatedby an operator for momentarily interrupting the source.
 12. A receivingand displaying system which senses and displays an identifying decimaldigit from a radio signal which is modulated by an identification signalcontaining one or more frequencies selected from a group of fourfrequencies in accordance with a binary coded decimal digit whichcorresponds to the identifying decimal digit to indicate the location ofan emergency condition, comprising means for receiving the modulatedradio signal and detecting the identification signal; four filter meansresponsive to the respective four frequencies in the identificationsignal for producing parallel signals corresponding to the binary codeddecimal digit; each of said four filter means being non-responsive tosignals of less than a predetermined continuous duration; meansresponsive to the signals produced by the four filter means fordisplaying the identifying decimal digit to indicate the location of theemergency condition; four memory means actuated by the respectivesignals from the four filter means for continuing the operation of thedisplaying means to display the decimal digit after the termination ofthe radio signal until reset by an operator; and timing means responsiveto the operation of a memory means for disabling the receiving anddetecting means and for enabling the operation of the displaying meansafter the periods of operation of all the four delay means.
 13. A systemas defined in claim 12 wherein the timing means for disabling thereceiving and detecting means and for enabling the displaying meansincludes: a unijunction transistor timing circuit having a predetermineddelay which is greater than the difference between the delays of any twoof the four delay means; means responsive to the actuating of any of thefour memory means for operating the unijunction timing circuit; a relayhaving a contact arm for normally engaging a first contact, said contactarm disengaging the first contact and engaging a second contact when acoil of the relay is energized, said contact arm connected to a voltagesource, said first contact connected to the receiving and detectingmeans, said second contact connected to the displaying means; a siliconcontrolled rectifier having its anode and cathode in series with thecoil; and means connecting an output of the unijunction transistortiming circuit to a control electrode of the silicon controlledrectifier for energizing the coil after the predetermined delay of thetransistor timing circuit to disable the receiving and detecting meansand to enable the displaying means.
 14. A system as defined in claim 12which includes: four memory means actuated by the respective signalsfrom the four filter means for continuing the operation of thedisplaying means to display the decimal digit after the termination ofthe radio signal until reset by an operator.
 15. A system as defined inclaim 12 wherein each of the four filter means includes: a tuning forkfilter, and a delay means between the respective filter and thedisplaying means for preventing the operation of the displaying meansfor a predetermined continuous duration of the presence of anidentification signal.
 16. A system as defined in claim 12 wherein eachof the four filter means includes a tuning fork filter.